I believe that certain situations and factors are repeated on an annual basis that lead to significant investment opportunities for the astute fan of sports. Without getting too specific, groups of humans suffer from cognitive biases when judging likely outcomes and assigning probabilities to those outcomes. These errors are frequently repeated and lead to significant reward opportunties with relatively low risk. These biases are magnified in both long term (season predictions) and short term (in game trading).
I believe that effort trumps talent in professional sports leagues. I can look at teams with added motivation, and I can look for teams with less motivation than their opponents. Essentially, a demotivated team is as un-effective as a motivated team is effective. Both disparities, if unnoticed by the general population, create investment opportunities. This also manifests itself in "mini-playoff" games between good teams and bad teams.
I believe that macro level trends of energy take course throughout the professional athlete season, most extensively in the NBA. These macro trends must be studied and analyzed to be properly understood. I also believe they are not understood or studied currently, and if mastered can lead to significant investment opportunities.
I believe some factors are not accurately gauged by the betting and watching public. These factors repeat themselves.
Lastly, I believe that an astute, focused, and educated person can consistently win games and make money betting on sports.